Intestinal iron absorption and metabolism will be studied by various in vitro biochemical and physiological techniques. Intestinal ferroxidase activity will be measured in various species and correlated with iron absorption. Characterization of the genetic defect in iron absorption in the mouse with sex-linked anemia (sla) will be pursued. This will include further characterization of the iron binding substances in normal and sla mouse intestine. Further studies are planned to identify the particle bound iron complexing material that has been extracted from rat intestine with sodium dodecyl sulfate.